Senate candidate Johnson leads Feingold in recent polls

Sep. 27, 2010

Written by

Gannett Wisconsin Media

How to read a poll

In the next month, voters will be inundated with polls conducted by political parties, media organizations and others. Here are a few tips for sifting through the data.- Check the sample size. How many people were asked about the poll subject?- Look at the margin of error. Polls will list a +/- percentage that shows the actual range each candidates' support falls in. If there's an overlap when the margin's added in, it means it's hard to project the results on to the general population.- Pay attention to whether the poll was conducted by humans or robot callers. Robo-call surveys can be less reliable.- Check who was polled. Was it likely voters? Registered voters? A purely random sample of state residents? A list of voters who cast a ballot in a certain year's election? Different samples can yield different results.- Know when was the poll conducted. Polls after primary elections and conventions will show a "bump" for a week or so afterward.Sources: Wendy Scattergood and Martin Farrell

Rasmussen Reports has Johnson leading Feingold 51 percent to 44 percent in a survey conducted the day after Johnson's primary election victory. Public Policy Polling has Johnson ahead 52-41 in a poll conducted over last weekend. And CNN/Time has Johnson up 51-45 percent among likely voters, though a CNN/Time poll of registered voters on the same day gave Feingold a 48-46 lead.

Political scientists at area colleges say Johnson's lead may not be as comfortable as it looks when presented on paper.

Wendy Scattergood, of the St. Norbert College Survey Center, said the timing of the Rasmussen poll and the margin of error in all the polls make this a closer race than any of the results may indicate. She also said the CNN/Time poll used real people to conduct the survey, while both the Public Policy and Rasmussen polls were conducted using automated calls, which can be less reliable.

"Yeah, it looks like Ron Johnson's a little bit ahead. And there are some that have him way ahead," Scattergood said. "But if you look at them as a whole and include the error margins, he looks like he's ahead, but it's not a lost cause for Feingold. Those figures will change a little bit as we go through October."

Ripon College Professor of Political Science Martin Farrell pointed out that the results differ based on whether likely voters or registered voters are polled, when the polls are conducted and how the list of those polled is developed, whether it be from a voting list, a random sample of statewide residents or another source.

"My understanding is that those numbers they're presenting, in all of those, are among likely voters. When they look only at registered voters, Feingold does better," Farrell said. "It means turnout will be crucial. Right now, the more conservative forces are more fired up and they're more sure they're going to vote. That's why likely voters are leaning toward Johnson. Feingold supporters and left-leaning independents seem demoralized a little bit. But a big turnout will help."

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Farrell said the message the combined polls send, even when considering timing and methodology differences, shouldn't be ignored by Feingold and his supporters.

"If I were a Feingold supporter, I wouldn't take it with a grain of salt. I'd take it seriously," Farrell said. "Ron Johnson has a good chance to win this election. Voters are angry at incumbents and he's been there for 18 years."

Scattergood, whose students will be conducting their own polls for Wisconsin Public Radio in October, added that poll results even closer to the election could vary from the Nov. 2 election results for reasons that range from debate performance to news reports to weather conditions on Nov. 2.

"What's important for people to look at is to consider them all together and to be a good consumer of polls," Scattergood said. "They're snapshots in time, not the people who are guaranteed to show up and cast a ballot."